Astro-Physics Thread-On Extension for 2.7" Focuser - Length 1.75".

It threads directly into the drawtube and contains knife-edge baffles. The 2" adapter mentioned below can be either ADA200 or ADA2003.

Applications:
Use with the Telecompressor for CCD Imaging: Remove the 2" adapter from the focuser drawtube, thread on the Telecompressor, then A3502 and the 2" adapter. Use this 1.75" length with your SBIG ST-8/ST-10 or Finger Lakes Instruments CCD cameras (without a Color Filter Wheel) to provide the optimal 0.75x compression.

As an extension: Remove the 2" adapter from the focuser drawtube, thread on A3502, then thread the 2" adapter on the other side. Note, you can thread two of these extensions together or with A3504, A3503 or A1008 to form a longer tube.